1 files changed, 47 insertions, 0 deletions
diff --git a/packages/testnet-faucets/src/ts/dispatch_queue.ts b/packages/testnet-faucets/src/ts/dispatch_queue.ts
new file mode 100644
index 000000000..94d094203
--- /dev/null
+++ b/packages/testnet-faucets/src/ts/dispatch_queue.ts
@@ -0,0 +1,47 @@
+import { intervalUtils } from '@0xproject/utils';
+import * as _ from 'lodash';
+
+const MAX_QUEUE_SIZE = 500;
+const DEFAULT_QUEUE_INTERVAL_MS = 1000;
+
+export class DispatchQueue {
+    private _queueIntervalMs: number;
+    private _queue: Array<() => Promise<void>>;
+    private _queueIntervalIdIfExists?: NodeJS.Timer;
+    constructor() {
+        this._queueIntervalMs = DEFAULT_QUEUE_INTERVAL_MS;
+        this._queue = [];
+        this._start();
+    }
+    public add(task: () => Promise<void>): boolean {
+        if (this.isFull()) {
+            return false;
+        }
+        this._queue.push(task);
+        return true;
+    }
+    public size(): number {
+        return this._queue.length;
+    }
+    public isFull(): boolean {
+        return this.size() >= MAX_QUEUE_SIZE;
+    }
+    public stop() {
+        if (!_.isUndefined(this._queueIntervalIdIfExists)) {
+            intervalUtils.clearAsyncExcludingInterval(this._queueIntervalIdIfExists);
+        }
+    }
+    private _start() {
+        this._queueIntervalIdIfExists = intervalUtils.setAsyncExcludingInterval(
+            async () => {
+                const task = this._queue.shift();
+                if (_.isUndefined(task)) {
+                    return Promise.resolve();
+                }
+                await task();
+            },
+            this._queueIntervalMs,
+            _.noop,
+        );
+    }
+}